Python Interview - Microwave

Prompt.md

The Microwave

Within one hour, design and implement the behavior of a microwave oven.

It has a numeric keypad and a START button. You are responsible for the logic triggered when any of these buttons is pressed.

• Pressing a numeric key sends your code one digit.
• Pressing START tells your code to start "cooking".

This microwave is not fancy. It cannot be stopped or paused once started. Input cannot be cleared. There is no “quick cook” option.

You are not responsible for building a UI or an interactive application. Write functions that might be called as each button is pressed. Use print statements as a substitute for user feedback.

Print what the display will show after each number press. If receiving the button presses for “1”, “3”, and “5”, your code could print "00:01", "00:13", then "01:35".

While cooking, print what the display will show once a second. After “START” is pressed, your code could print “01:34”, “01:33”, “01:32”, and so on.

solution.py

# solution.py

import time

class MicrowaveOven:
    """
    MicrowaveOven handles logic related to cooking
    """
    def __init__(self, cli=False):
        self.__cli = cli

    def cook(self, time):
        if self.__cli:
            print(f"(Food will cook for {time} seconds.)")
        else: 
            raise AttributeError("CLI set to 'False' but non-CLI features have not yet been implemented")

class MicrowaveRunner:
    """
    MicrowaveRunner handles the logic related to user input
    """

    def __init__(self, cli=False):
        self.__cli = cli
        self.__oven = MicrowaveOven(cli)
        self.__timer = []

    def __str__(self):
        return self.screen()

    def screen(self) -> str:
        output = "".join(self.__timer)
        if len(output) == 1:
            output = f"00:0{output}"
        elif len(output) == 2:
            output = f"00:{output}"
        elif len(output) == 3:
            output = f"0{output[0]}:{output[1:]}"
        elif len(output) >= 4:
            output = f"{output[0:2]}:{output[2:4]}" # Ignore anything beyond the fourth digit
        return output

    def input(self, value) -> bool:
        """ Adds user input value to timer """
        if len(value) > 1:
            value = value[1] # Avoid mistaken input beyond a single digit
        if len(self.__timer) < 4:
            self.__timer.append(value)
            return True
        else:
            if self.__cli:
                print("(Bad Beep!\a)")
            return False

    def convert_time(self) -> int:
        screen = self.screen()
        minutes = int(screen[0:2])
        seconds = int(screen[3:5])
        timer = (minutes * 60) + seconds
        return timer if timer < 5999 else 5999

    def cli_start(self) -> None:
        timer = self.convert_time()
        while timer:
            mins, secs = divmod(timer, 60)
            display = '{:02d}:{:02d}'.format(mins, secs)
            print(display, end="\n")
            time.sleep(1)
            timer -= 1
        print("Good Beep!\a")

    def start(self) -> None:
        """ This function has not been implemented """
        if self.__cli:
            self.cli_start()
        else:
            raise AttributeError("CLI set to 'False' but non-CLI features have not yet been implemented")

if __name__ == "__main__":
    microwave = MicrowaveRunner(cli=True)
    start = False
    
    while not start:
        value = input("> ")
        if value.lower() == "start":
            break
        microwave.input(value)
        print(microwave.screen())

    microwave.start()